The instantaneous state of a vehicle is defined by state parameters for vehicle pitch, vehicle roll and vehicle yaw. The vehicle state changes continuously while the vehicle is in motion, for example due to acceleration/deceleration of the vehicle and changes in the gradient of the surface on which the vehicle is travelling. The vehicle state is used by on-board vehicle dynamic control systems, for example to control vehicle stability.
In the automotive field it is known to employ an inertial monitoring unit (IMU) to continuously monitor vehicle acceleration in six degrees of freedom to monitor the vehicle state. It would be desirable to obtain more reliable data from the IMU and potentially to simplify the IMU by reducing the number of degrees of freedom in which acceleration and rates are measured. One approach is to estimate the vehicle state using measured dynamic parameters. However, global state estimations calculated from vehicle sensors are susceptible to noise and, in certain conditions, high error levels. Signal filtering can be used to lessen undershoots and overshoots in these conditions. However, for large signal-to-noise ratios heavy filtering is required which result in poor estimations in transient conditions.
It is against this backdrop that the present invention(s) has been conceived. At least in certain embodiments, the present invention seeks to overcome or ameliorate some of the shortcomings associated with known vehicle state estimation systems.